By eleven o’clock, Trinity had the house to herself. She was cleaning the kitchen and listening to the TV news.

Her father had been picked up in a huge Dodge Ram by three of his old friends from his building union. He had told her that they would be spending the day angling for channel catfish at Reseda Park Lake, but he hadn’t even made a point of taking his fishing rod with him.

She knew that in reality the four of them would be drinking their way through half a dozen six-packs of Budweiser and telling off-colour jokes and that they would be lucky to find their way home without being stopped by the cops.

Rosie had gone off in her shortest shorts to meet some of her girlfriends at La Michoacana ice-cream parlour on Sherman Way. Trinity had given her $10 left over from the money that Sabina had lent her so she could buy herself a blackberry cheese paleta and a Coke.

Like her father, Rosie hadn’t told her the whole truth. Trinity was sure that Rosie would be meeting not only her girlfriends but a gang of boys who hung around the corner of Sherman Way and Baird Avenue. They called themselves the Toreros, but Trinity found it hard to imagine any collection of young men who looked less like bullfighters. She called them the Desaliñados, the Scruffies, which always made Rosie explode into one of her tirades.

‘You don’t even know them! They’re totally dope! They’re goat!’

As for Buddy, he had gone off to meet his pal José. What mischief he and José got up to together, Trinity could only guess, but somehow Buddy always seemed to have pocketfuls of loose change, so he hardly ever asked her for money.

Trinity was wiping the work surface under the window when she heard the news anchor mention Margo’s name. She went through to the living room in time to hear the anchor saying, ‘—medical examiner confirmed this morning that Ms Shapiro took her own life by  pouring gasoline over herself and setting herself alight. An inquest has been opened and adjourned but in the meantime the West Valley police are not looking for anybody else in connection with Ms Shapiro’s death.’

‘What?’ said Trinity out loud, staring at the television. ‘She couldn’t have committed suicide! She wouldn’t have done! And that man who came running out! What about him?’

She closed her eyes for a moment and she could picture Margo sitting in that restroom stall, her face shrivelling and crinkling and both hands held up as if she were begging. She could see Margo’s green dress flaking and the flames leaping up around her like dancing ghosts.

And then she thought: the flames were blue. Transparent, but definitely blue. Surely gasoline doesn’t burn blue.

She had watched her father burning cardboard boxes and garden rubbish in the back yard, and he had splashed gasoline onto the fire to get it going. He had almost set his dungarees alight, too. But the flames had been orange.

She picked up her old Dell laptop and sat down on the couch. First of all she checked on Google what colour gasoline burned. There was even a video of a man setting light to glass jars filled with six different types of fuel, from aviation fuel to diesel, and sure enough, gasoline burned orange.

So what was it that could have given off those ghostly blue flames? She watched three more videos and read two Wikipedia entries on combustion. By the time she had done that, she was convinced that Margo had been doused not in gasoline but in methanol, or what used to be called wood alcohol. Methanol was a highly flammable  solvent, but  it was used in the manufacture of scores of different everyday products, from plastics to antifreeze to headache pills. Because of that, she guessed it probably wasn’t hard to get hold of it.

She phoned Nemo. He took a long time to answer, and when he did she could hear traffic noises in the background.

‘Mr Frisby – Nemo. It’s Trinity Fox.’

‘Oh, sure. How’s it going, Trinity? Feeling a tad better, I hope?’

‘Well, not really. I just heard on the news about Margo’s autopsy. The medical examiner confirmed that first report and said that it was suicide.’

‘But you – you’re still quite sure that it wasn’t?’

‘I saw her burning with my own eyes, Nemo, and the flames were blue. They said that she set fire to herself with gasoline, but gasoline doesn’t burn blue. I’ve been checking and I’m practically one hundred per cent sure that she was splashed over with methanol. And that guy who came running out and nearly knocked me over, I’m still sure he did it.’

‘Methanol? You’re sure? I once had a case when a woman in Winnetka treated her husband to a methanol cocktail. That stuff’s not just flammable, it’s toxic. It can blind you or kill you if you drink it. I never saw anybody die in such agony. And all the time his wife was laughing like a hyena.’

Nemo paused for a moment, and Trinity thought  she heard him talking to someone else. But then he said, ‘Believe me, Trinity, I’ve been thinking about your friend over and over, but you see the problem we have here? You saw those blue flames, but you were the only person who did, and the forensic guys claim they found a container at the scene that still had traces of gasoline inside it. So you can understand what conclusion the ME was most likely to come to. Between you and me, he always plumps for the most obvious answer. Makes his life less stressful.’

‘But did they check that container for Margo’s fingerprints and DNA? And they say they found a cigarette lighter on the floor too. Did they check that?’

‘I have no idea. I can ask Sergeant Weller but I’m not sure he’ll know and even if he knows I’m not sure he’ll tell me, and I’ll tell you for why. I had an unexpected visitor yesterday evening. After what he said to me, I’m pretty much persuaded that you’re right, and that your friend did not take her own life.’

‘A visitor? Who was it?’

‘Some creepy minion from the IAG… that’s the internal affairs department. And guess what? He told me in no uncertain terms that the powers that be in the police force want me to forget about what happened to your friend Margo. Can you believe that? Right now I’m out running a couple of errands but I was going to call you later to bring you up to speed.’

‘They want you to forget about it? Why? I’d have thought they’d appreciate any help that you could give them.’

‘Well, me too. But all they’ve managed to do is make me ask even more questions than I had to start with. If your friend really did commit suicide, why should it worry them? And what makes me even more suspicious is that they’ve given out the results of the autopsy so soon. Like, within less than forty- eight hours. Post-mortems take days, as a rule. Sometimes weeks, even, depending on how the deceased was discovered, and how long they’d been dead.

‘Either your friend’s body was examined by the fastest pathologist in the west, or else it hasn’t been examined at all. I tried to call Jim Bryce about it. Twice I called him, but he never returned my call, which is not at all like him.’

Trinity said, ‘I don’t know what to do now. But she was one of my closest friends and if she’s been murdered I want to find out why. I can’t just let it go.’

‘Okay. I’m with you. I’m filling up with gas right now and I have to pick up some groceries at the Valley Marketplace or else my wife will be giving me a methanol cocktail too. But if you’re free I can come meet you afterwards.’

‘Yes, come round. I’m here all day, on my own.’

‘I’ll tell you something, Trinity – when you suspect that somebody’s trying to flimflam you and cover up the real cause of death, the way to find out what actually happened is to make out that you believe them. That way, you can almost always pick their story apart and without realising it they’ll help you to do it. They won’t be able to remember all the details they’ve made up, and there’ll always be important things that they’ve forgotten to invent. The ME’s saying she committed suicide? Okay – why did she commit suicide? Nobody commits suicide for no reason. Was she depressed? Was she being trolled? Did she leave any kind of suicide note?’

‘All she told me was that she was scared.’

‘Do you know where she lived? Do you know her parents, or her relatives, or her neighbours?’

‘Yes, I know her mom and dad. And her sister.’

‘Right. That’s where we start. I’ll see you in about an hour. And Trinity?’

‘What?’

‘I have a motto, and maybe it’ll be good for you too. When somebody’s trying to deceive you, their choice of lies is even more illuminating than the truth. I can’t remember who said that. Some thousand-year-old Buddhist swami, I expect. But it’s always worked for me.’